Numerous assemblies have been conceived for shoring the sidewalls to a construction trench. Griswold U.S. Pat. Nos. 4,019,329 and 4,058,983, for example, both disclose a boxlike construction, with a pair of spaced apart sidewalls for vertical disposition in a newly dug trench or ditch. A plurality of spreader pipes connect the sidewalls while allowing for some limited pivotal movement therebetween. To remove an assembled Griswold box from its trench after project completion, a plurality of lifting rings 82 are provided for sliding along one or more spreader pipes 18 of this prior art configuration. With a crane hook and some cable threaded through its lifting rings, the Griswold apparatus can be extracted from the hole in which it was used.
An improvement to basic trench box designs is disclosed in Kundel U.S. Pat. Nos. 5,533,838 and 5,669,738. Therein, a modular trench box design can be assembled from a plurality of vertical sheeting panels slid downwardly into a spaced-apart guide frame. In order to remove this box design from its trench after project completion, there are provided aligned circular apertures and inserts on multiple upper sheeting panels. A lifting insert fits in said apertures for removing the trench box with a crane or other mechanical lifting apparatus.
A further improvement to trench box designs is shown and described in Kundel U.S. Pat. No. 6,443,665. For this design, a plurality of stacked panels 20 are slid downwardly over a hook or J-shaped connector at opposite ends of each panel to form a pair of trench box sidewalls spaced apart by support bars 50. Once fully assembled, this box is moved into proper position in a trench with chains hooked through D-rings 37 on the connector frames using the boom of a backhoe. Thereafter, the chains are removed and the box pound down into its desired depth in the trench.
Another more mechanically complicated trench box configuration entails a shape with sidewalls, through which conduit may be continuously laid. The separated sides to the box and method of Hatch U.S. Pat. No. 4,714,381 may be advanced by pulling the box forward and tapping it down at one end with the arms of an excavator. Burdine U.S. Pat. No. 5,336,023 teaches a self-propelled trench box having rotatable drive tracks hydraulically driven like the tracks on a military tank. Multiple lift tubes 48 on each sidewall panel serve as lifting locations for removing the box from its trench by hook up to a crane or backhoe. And finally, Wilkinson U.S. Pat. No. 5,931,608 shows a trench shoring transport device that includes a wheeled frame. Below that frame which is adjustable in width, there is suspended one or more trench boxes that can be raised at opposite ends with one or more hydraulic arms. In one preferred embodiment, these hydraulic arms remain attached to respective auxiliary spreaders at opposite trench box ends.
At the present time, there are no easily adaptable attachments for the arm of an excavator for lifting and/or moving a trench box from a first position to a second position along the trench. In any cases, an excavated trench tends to be substantially elongated and continuous in order to lay utilities, such as, for example, lengths of water lines, sewer pipe, cable or electric lines. After work within the immediate trench box area has been completed and the box should be moved along the length of the trench, but not yet fully re-moved from the trench, workers have been observed using the excavator shovel or bucket end to forcibly push or pull the box forward, along the substantially horizontal trench floor. Sometimes, the excavator bucket face (or teeth end) is used for partially lifting the box up and away from the mud of trench sidewalls and/or floor. Then with these same bucket teeth, the trench box proper is either pulled toward or pushed away by the excavator arm. That prior practice is fundamentally unsafe. The trench box itself can easily slip from the excavator bucket during transit.
Ideally, what would be desirable is an attaching apparatus to an excavator that easily, yet fairly quickly, secures to the working end of the excavator area. That attachment is shaped so that it can be easily maneuvered between the spreader bars at the forward end of a typical trench box design. Then by mere manipulation of the excavator arm, the attaching apparatus is positioned between, then rotated downward so that the lower hook ends of the attachment engage against one of said trench box spreader bars. Another surface of that same attachment contacts with or otherwise engages the adjacent spreader bar for moving the box forward. In a preferred embodiment, this engagement would not have to lock on to any portion of the trench box. On the contrary, after the box has been moved from its first location to its next, the attachment can be easily and rapidly removed from between adjacent spreader bars merely by maneuvering or tilting the excavator arm and attachment backwards a few degrees, then pulling the attachment back, out from between the pair of spreader bars and away from the trench box once relocated at its second working position.